Autoset and torsional bearing folder

ABSTRACT

A folding machine has folding rollers mounted to a frame by means of torsional bearings. The torsional bearings provide a force for biasing movable rollers toward complementary rollers. In some embodiments the torsional bearings are also used as a means for adjusting and measuring the movable-roller biasing force. In these embodiments, torque arms are connected to the torsional bearings to be used for both adjusting and indicating this biasing force. In another embodiment, a lifter arm is provided for separating a movable roller mounted on a torsional bearing from a stationary roller. A special linkage is provided for ensuring that the movable roller, when adjusted, moves in an arc about a central axis of the torsional bearing. A fixed lifter arm bracket is described for use in conjunction with the lifter arm. By inserting a sheet of paper between the lifter bracket and the lifter arm the movable roller is moved in an arc about the central axis the proper fixed distance from the stationary roller.

United States Patent [191 Boyer [4 1 Oct. 28, 1975 AUTOSET AND TORSIONALBEARING FOLDER [75] Inventor: Harold E. Boyer, Anna, Ohio [73] Assignee:Bell & Howell Company, Sidney,

Ohio

[22] Filed: May 10, 1974 [21] Appl. No.2 468,683

Related U.S. Application Data [63] Continuation of Ser. No. 299,704,Oct. 24, 1972,

abandoned.

[52] U.S. Cl. 270/68 [51] Int. Cl. B65h 45/14 [58] Field of Search270/68 R, 68 A; 64/14; 267/21; 287/85 [56] References Cited UNITEDSTATES PATENTS 2,712,742 7/1955 Neidhart 64/14 2,729,442 1/1956 Neidhart64/14 X 3,021,134 2/1962 Appell 270/68 A 3,089,695 5/1963 Brooks....270/68 A 3,226,819 1/1966 Wendel 64/14 X 3,328,026 6/1967 Baritizal270/68 A Primary ExaminerJoseph S. Reich Assistant ExaminerV. MillinAttorney, Agent, or Firm Griffin, Branigan and Butler [57] ABSTRACT Afolding machine has folding rollers mounted to a frame by means oftorsional bearings. The torsional bearings provide a force for biasingmovable rollers toward complementary rollers.

In some embodiments the torsional bearings are also used as a means foradjusting and measuring the movable-roller biasing force. In theseembodiments, torque arms are connected to the torsional bearings to beused for both adjusting and indicating this biasing force.

In another embodiment, a lifter arm is provided for separating a movableroller mounted on a torsional bearing from a stationary roller. Aspecial linkage is provided for ensuring that the movable roller, whenadjusted, moves in an arc about a central axis of the torsional bearing.A fixed lifter arm bracket is described for use in conjunction with thelifter arm. By inserting a sheet of paper between the lifter bracket andthe lifter arm the movable roller is moved in an arc about the centralaxis the proper fixed distance from the stationary roller.

16 Claims, 6 Drawing Figures US. Patent Oct. 28, 1975 Sheet 1 on3,915,446

U.S. Patent Oct. 28, 1975 Sheet 2 Of3 3,915,446

,6 v FIG? FIG. q fi US. Patent Oct. 28, 1975 Sheet 3 of 3 3,915,446

FIG. 5 99 AUTOSET AND TORSIONAL BEARING FOLDER This is a continuation ofapplication Ser. No. 299,704, filed Oct. 24, 1972, now abandoned.

BACKGROUND OF THE INVENTION This invention relates broadly to the art offolding machines and more particularly to buckling-type foldingmachines.

Stated briefly, a buckling-type folding machine normally comprises aseries of rollers and stop assemblies. A sheet of paper to be folded isinserted between two rotating rollers of a first roller set and isdriven by these two rollers into the mouth of a stop assembly. A forwardedge of the sheet eventually strikes a stop in the stop assembly;however, the two rollers continue to feed the sheet forward. Thus, thesheet buckles and the bulge of this buckle eventually extends betweentwo rollers of a second roller set. These rollers fold the sheet at thebulge and feed this folded edge into a second stop assembly. Uponstriking a second stop there is a new buckle in the sheet and thisbuckle is in turn inserted between two rollers of a third roller set.This process continues until the sheet is folded the desired number oftimes.

In most buckling-type folding machines at least one roller of eachroller set is adjustable so that the folding machine can be made toaccommodate different sizes and weights of paper sheets. In this regard,prior-art folding machines normally must have their rollers adapted forseparate adjustment on each job.

Basically, there are two types of adjustments that are made to therollers.

The first type of adjustment varies the amount of force or load that themovable rollers continuously exert toward the other rollers of theirrespective sets. In this regard, springs are normally adjusted toconstantly urge the movable rollers toward the other rollers of theirsets thereby applying requisite pressures between the rollers forobtaining appropriate folds.

The second adjustment relates to varying the positions of the movablerollers relative to the other rollers of their respective sets so thatvarious thicknesses of paper stock may be folded by the machine. Thisadjustment is hereinafter referred to as the roller gap adjustment. Inthis regard, movable rollers are normally mounted on levers so thatrotation of the levers varies the positions of the rollers. An exampleof such devices is found in US. Pat. No. 3,021,134 to Appell.

In some systems the roller gaps are set by placing pieces of paper stockbetween ends of the rollermounting levers and stationary brackets sothat the movable rollers mounted on these levers are moved thethicknesses of the sheets. An example of such systems is described inWest German Pat. No. 1,436,558.

One difficulty with many of the prior art folding devices is that theirload adjusting mechanisms employ large numbers of coil springs. In thisrespect, coil springs are somewhat cumbersome in that they require undueamounts of space to operate properly and require frequent adjustment.

Also, such springs tend to wear out relatively quickly. Not only doesthis feature require frequent replacement of springs, but also theresiliency of the springs, when being used, tends to change ratherdramatically over relatively short periods of use. Thus it is difficultfor operators to predict the proper settings of springs for a certainjob, even though the same jobs may have been performed previously on thesame folding machines.

Therefore, it is an object of this invention to provide a foldingmachine having an adjusting mechanism which employs resilient elementswhich are generally more durable than metallic springs; operate moreuniformly; and do not require a large amount of adjustment.

Still another difficulty with prior art folding devices is that theroller gaps must be adjusted for most jobs even though the paperthicknesses of several job varies very little. Thus, it is yet anotherobject of this invention to provide a folding machine wherein a singleroller-gap setting accommodates relatively large variations of paperthicknesses.

A difficulty encountered in adapting torsional bearings to be used withbuckle-type folding machines is that there is a certain amount of playin torsional bearings (that is, a small amount of lateral motion as wellas rotational motion); thus making it difficult to obtain an accurategap setting for torsional-bearingmounted rollers. Therefore, it isanother object of this invention to provide a folding machine having atorsional-bearing-mounted roller wherein the gap setting can beaccurately adjusted.

SUMMARY OF THE INVENTION According to the principles of this invention,movable rollers of a buckling-type folding machine are mounted on armswhich, in turn, are mounted on a folding machine frame by means oftorsional bearings.

In some embodiments, the amount of loading applied by the movablerollers to stationary rollers is controlled by controlling the positionsof central square shafts of the torsional bearings. Torque arms areprovided for both rotating the central square shafts and for indicatingthe positions of the central shafts. Thus, the torque arms provideindications of loading pressures between rollers.

In other embodiments of the invention a lifter arm is provided forcausing a torsional-bearing-mounted roller to move in an are about acentral axis of the torsional bearing in response to movement of thelifter arm. Thus, the lifter arm can be used for adjusting roller gap.In addition, a system is disclosed wherein proper gap adjustment isobtained by inserting a sheet of paper between the lifter arm and astationary bracket.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects,features and advantages of the invention will be apparent from thefollowing more particular description of preferred embodiments of theinvention, as illustrated in the accompanying drawings, in whichreference characters refer to the same parts throughout different views.The drawings are not necessarily to scale, emphasis instead being placedupon illustrating principles of the invention in a clear manner.

FIG. 1 is a side elevation of a series of bucklefolder rollers, some ofwhich are mounted to a frame by means of torsional bearings;

FIG. 2 is a side elevation of a buckle-type folding machine roller setwhich is mounted according to principles of this invention;

FIG. 3 is a top view of the roller set shown in FIG. 2;

FIG. 4 is an exploded view of a torsional bearing assembly and itsmounting means; and

FIG. 5 is an isometric view of a buckle-type roller mounted according toprinciples of this invention with a mounting means including a lifterarm and a torque arm assembly.

FIG. 6 is a pictorial view illustrating a spring loaded ball protrudingfrom a fine adjusting knob broken out of FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to FIG. 1, thefolding system depicted therein comprises five movable, or adjustable,rollers 11-19, a stationary fixed roller 21 and three stop assemblies23-27.

Each of the five movable rollers 11-19 are respectively mounted on oneof five torsional bearing assemblies 29-37.

Each of the torsional bearing assemblies 29-37 comprises a rollermounting arm 39, a roller mounting bushing 41 and a torsional bearing43. One such torsional bearing which can be used in preferredembodiments of this invention is described in US. Pat. No. 2,712,742 toNeidhart.

The torsional bearing 43 includes a tubular housing 45, having asomewhat square cross-section, a square shaft 47, and cushioningelements 49. The tubular housing 45 is fixedly attached to the rollermounting arm 39. Normally, the position of the square shaft 47 can befixed relative to a folding machine frame (not shown). Thus, withrespect to a neutral position when there is relative rotation betweenthe roller mounting arm 39 and the square shaft 47, the cushioningelements 49 are compressed. This compression produces a torque tendingto rotate the roller mounting arm 39 to the neutral position where thecushioning elements 49 are compressed to a lesser extent.

Normal torsional bearings employ cushioning members which have ahardness measuring 70 durometers or so. In preferred embodiments of thisinvention, however, the cushioned members have a hardness of 50durometers to obtain a torsional bearing of the preferred stiffness, butother hardness ratings can be satisfactorily employed.

When the movable rollers 11-19 are moved from their neutral positions,they are biased by their respective torsional bearings 42-46 toward theneutral positions. It follows that the amounts of biasing forces exertedby the movable rollers 11-19 on rollers they contact, depends on theattitudes of the square shafts 47 relative to the roller mounting arms39.

Turning now to the operation of the system shown in FIG. 1, a sheet ofpaper 51 is inserted between the first movable roller 11 and thestationary roller 21. These rollers are adapted by a means (not shown)to drive the sheet of paper 51 into a first stop assembly 23. Eventuallya forward edge of the sheet of paper 51 contacts a stop member 53. Atthis point, the sheet of paper 51 buckles and a buckle bulge movesbetween the stationary roller 21 and the second movable roller 13. Thesheet of paper is folded as the bulge area moves between these lattertwo rollers and the folded edge is driven into the second stop assembly25, whereupon the same buckling procedure described above is repeated.That is, another fold occurs between rollers 13 and and another betweenrollers 15 and 17. Eventually, the folded sheet of paper is guided by aguide 55 between the fourth and fifth movable rollers 17 and 19 and fedto a suitable receiver.

The square shafts 47 of the torsional bearings 43 are preset to cause adesired biasing of torques on the movable rollers 1l-19. Hence, as asheet of paper passes between two given rollers they are allowed tospread apart by respective ones of the five torsional bearings 42-46 sothat the bearings exert a correspondingly desired torque.

Not only does the system described above eliminate the use of priortypes of space consuming springs, but experiments have shown that,without readjustment, this system accommodates a much wider range ofpaper-sheet weights and thicknesses than the former types ofspring-biased systems. The reason that this system can accept a widervariety of sheets without readjustment is not fully understood but theresults have been outstanding. Moreover, when used in the abovedescribed manner the torsional bearings have been found to have a muchlonger useful life than most coil springs. Hence, not only do theyrequire less frequent replacement but their performance characteristicsdo not change as rapidly or drastically as those of coil spring types offolder adjustments.

FIGS. 2, 3, and 4 depict a portion of a modified embodiment of thesystem shown in FIG. 1 which illustrates another advantage oftorsion-bearing-mounted rollers over conventional spring biased rollers.With reference to FIGS. 2 and 3, a stationary roller 57 and a movableroller 59 form a roller pair. The movable roller 59 is mounted by meansof its shaft 60 and bushings 61 on torsional bearing assemblies 62which, in turn, are mounted on frame members 63 A and B by means of ashaft 65 having a round-cross-section. Shaft 65 is rigidly attached tosquare-cross-sectional shafts 67 of torsional bearings 69 which aresimilar to the torsional bearings 43 shown in FIG. 1. These bearings areshown in more detail in the exploded view of FIG. 4.

A torque arm 71 has a square aperture 73 (FIG. 4) for gripping thesquare shaft 67 of one of the torsional bearings 69. The shaft 65,torque arm 71, and torsional bearing assembly 62 are held together asshown by means of a flange 75, a washer 77, and a retaining ring 79which mates with an indentation 81 in the shaft 65.

A nut and bolt assembly 83 (FIG. 3) is used to fix the torque arm 71 atvarious positions along an elongated slot 85 (FIG. 2) in the framemember 6313. A graduated scale 87 provides an indication of the positionof the torque arm 71.

Overall operation of the FIGS. 2-4 embodiment is basically the same asoperation of the system of FIG. 1. That is, the square shafts 67 of thetorsional bearings 69 are set to cause a biasing torque on the torsionalbearing assembly 62. This torque, in turn, biases the movable roller 59against the stationary roller 57. The amount of biasing torque, however,can be easily modified by rotating the torque arm 71 in the slot 85,thus changing the attidute of the square shafts 67 which changes theneutral position of the torsional bearings 69.

The graduated scale 87 provides an indication of the angular position ofthe torque arm 71 which, in turn, provides an indication of the amountof pressure exerted by the movable roller 59 against the stationaryroller 57. Referring to FIG. 2, for example, the torque arm is adjacent0 on the graduated scale 87 at such time the movable roller 59 and thestationary roller 57 are in contact but no appreciable force is exertedby the movable roller 59 on the stationary roller 57. A differentsetting of the indicator results in a different force.

Turning lastly to FIG. 5 there is shown a roller-set assembly comprisingessentially a stationary roller 89, a movable roller 91, a torsionalbearing assembly 93, a torque arm 95, a lifter arm 97 and a fixedlifter-arm bracket 99.

The movable roller 91 is mounted on the torsional bearing assembly 93 inthe same manner as the movable rollers of FIGS. 1-4. The torsionalbearing assembly 93 also has a torsional bearing 101, similar to thetorsional bearings previously described. In this case the assembly ismounted on a folding-machine frame 103. Again, a square shaft 105 of thetorsional bearing 101 is rotatable relative to the frame 103, but isheld in a fixed position by means of the torque arm 95; and the torquearms angular position is adjustable by means of an adjusting screw 107in a slot 109. A graduated scale 111 provides an indication of theangular position of the torque arm 95.

The lifter arm 97 is rotatably mounted on a circular shaft 113 whichextends through the square shaft 105. A table 115 is formed at one endof the lifter arm 97 and a cradle 117 is formed at the other end of thelifter arm 97. The cradle 117 cradles a shaft 118 of the movable roller91 such that lifting movement of the cradle 117 causes the movableroller 91 to lift up from the stationary roller 89.

The table 115 is adjacent an anvil 1 19 which is a part of the lifterarm bracket 99. The lifter arm bracket 99 is fixed to the frame 103,however, the anvil 119 can be lowered and raised relative to the bracket99 by means of a threaded screw by rotating a knob 121. The location ofthe anvil 119 is such that movement of the portion of the table 115located adjacent the anvil 119 is in a 1:1 relationship with movement ofthe cradle 117.

In operation, the loading, or biasing, pressure exerted by the movableroller 91 toward the stationary roller 89 is controlled by rotating thetorque arm 95, as in the FIGS. 2-4 embodiment. In this regard, rotationof the torque arm 95 rotates the square shaft 105 thereby changing theneutral position of the torsional bearing 101. Again, a setting of 0indicates roller contact with virtually no loading force.

A gap can then be accurately set between the movable roller 91 and thestationary roller 89 by adjusting the position of the table 1 15. Thiscan be accomplished by inserting a piece of the paper stock to be foldedbetween the table 115 and the anvil 119, thereby causing the cradle 117to lift the movable roller 91 a distance from the stationary roller 89equal to the thickness of the paper sheet. At this point, the positionof the tension lever 95 can be readjusted if it is desirable.

The knob 21 provides an additional fine adjusting feature. In thepreferred embodiment, there is a spring loaded ball 130 in the anvil 119pressing downwardly to help hold a paper sheet between the anvil 119 andthe table 115.

It should be understood that the special shape of the lifter arm 97,which provides a cradle 117, produces an arcuate movement of the movableroller 91 about a central axis of the torsional bearing 101. If, forexample, the table 115 were attached directly to the torsional bearingassembly 93, arcuate movement of the table 1 15 may not produce asimilar arcuate movement of the movable roller 91 due to play in thetorsional bearing 101.

In summary, torsional-bearing mounted rollers on folding machines havethe following advantages among others:

A more compact folding machine is produced because the torsionalbearings generally take up less room than the levers and springs ofprior art systems. In this regard, torsional bearings also combine thefunctions performed by both bearings and springs of prior-artfolding-machines; thus torsional bearings also conserve space byeliminating parts.

As compared to most prior art systems torsionalbearing-mounted rollerscan accommodate a wider range of paper weights and thicknesses withoutreadjustments.

Torsional bearings are normally more durable than the metallic coilsprings of prior art systems. In this regard, experiments have shownthat torsional bearings last millions of cycles without reduction ofspring force; and comparative tests presently appear to indicate thattorsional bearings have life spans of as much as 20 times longer thanthose of coil springs.

There are generally fewer linkage problems with torsional bearingsystems than with most prior art systems, thus, less lubrication andmaintenance is required and joint freezing is reduced.

Torsional bearings are self damping and self aligning. Also because oflateral play in the torsional bearings a roller can be out of line orcanted; yet the roller still functions properly even though a sheet isinserted on only one side of the roller. This feature is sometimes saidto produce a floating roller effect.

A relatively uncomplicated system can be employed to adjust the constantpressure applied by a movable roller to a stationary roller. In thisregard, it is also significant that the systems for adjusting rollerpressure and roller gap are independent of one another and are in somerespects less complicated than some similar prior art systems whereinthe same linkage is used to provide both types of adjustment.

While the invention has been particularly shown and described withreference to preferred embodiments, it will be understood by thoseskilled in the art that various changes in form and detail may be madetherein without departing from the spirit and scope of the invention.For example, the torsional bearing described herein can take on variousforms, some of which are described in the previously referred to US.Pat. No. 2,712,742 to Neidhart.

The embodiments of the invention in which an exclusive property orprivilege are claimed are defined as follows:

1. A folding machine comprising a system of rotatable rollers mounted ona frame so that said rollers form bites therebetween for gripping andtransporting sheets to be folded, said folding machine including guidingmeans for guiding said sheets between said I bites so that some of saidbites, upon gripping and transporting said sheets, cause folds in saidsheets, said folding machine further including a roller mounting meanscomprising:

a roller mounting arm; a torsional bearing including a resilient meansfor mounting said roller mounting arm on said frame at a first areaalong said roller mounting arm; and

a roller mounting means for mounting a first roller on saidroller-mounting arm at a second area spaced from said first area alongsaid roller mounting arm; wherein,

said torsional bearing is preset so that said resilient means causes apredetermined biasing torque on said roller mounting arm to thereby urgesaid first roller toward a second roller so that a bite formed by saidfirst and second rollers produces appropriate folds in sheets of a giventhickness range.

2. A folding machine as claimed in claim 1 wherein said torsionalbearing comprises:

an inner shaft;

an outer housing; and

a cushioning member positioned between said inner shaft and said outerhousing; and

wherein is further included a torque adjusting means for adjusting theangular position of said inner shaft to cause said proper biasing force.

3. A folding machine as claimed in claim 2 wherein said torque adjustingmeans includes a gauge means for indicating the angular position of saidinner shaft.

4. A folding machine as claimed in claim 3 wherein said torque adjustingmeans includes an eleongated arm attached to said inner shaft.

5. A folding machine as claimed in claim 1 wherein is further included aroller positioning means for adjusting the position of said roller.

6. A folding machine as claimed in claim 5 wherein said rollerpositioning means is for causing causes said roller to rotate in an arcabout a central axis of said torsional bearing.

7. A folding machine as claimed in claim 6 wherein said rollerpositioning means comprises a lever which pivots about said central axisof said torsional bearing, said lever being linked to said rollermounting arm in such a manner as to cause said roller mounting arm torotate about said central axis in an arc in the same manner that saidlever rotates about said central axis.

8. A folding machine as claimed in claim 7 wherein said lever includes atable at one end thereof and a cradle at the opposite end thereof, andwherein is further included a fixed bracket adjacent to said tablewhereby a piece of material inserted between said table and said bracketcauses said roller to have a predetermined position.

9. A folding machine as claimed in claim 8 wherein said torsionalbearing comprises:

an inner shaft;

an outer housing; and

a cushioning member positioned between said inner shaft and outerhousing;

and wherein is further included a torque adjusting means for adjustingthe angular position of said inner shaft to cause said proper biasingforce.

10. A folding machine as claimed in claim 9 wherein said adjusting meansincludes a gauge means for indicating the angular position of said innershaft.

1 1. A folding machine as claimed in claim 10 wherein said torqueadjusting means includes an elongated arm attached to said inner shaft.

12. A folding machine as claimed in claim 1 wherein said folding machineincludes a series of rollers;

and a plurality of elongated roller mounting arms and torsional bearingsfor respectively mounting said rollers on said frame.

13. A folding machine as claimed in claim 1 wherein said torsionalbearing comprises:

an inner shaft;

an outer housing; and

a cushioning member positioned between said inner shaft and said outerhousing, said cushioning member producing a measurement of approximately50 on a durometer.

14. A folding machine as in claim 1 wherein the pivot point of saidtorsional bearing is located at a fixed distance from the axis ofrotation of said roller.

15. The folding machine of claim 1 wherein said roller mounting meansincludes an axle for said first roller and said torsional biasing meanscomprises an inner shaft, an outer housing, and a cushioning memberpositioned between said inner shaft and said outer housing; and whereinsaid folding machine further includes:

means connecting said inner shaft of said torsional bearing to said axlefor maintaining a fixed distance between the center of said torsionalbearing and said roller axle.

16. A folding machine comprising a system or rotatable rollers mountedon a frame so that said rollers form bites therebetween for gripping andtransporting sheets to be folded, said folding machine including guidingmeans for guiding said sheets between said bites so that some of saidbites, upon gripping and transporting said sheets, cause folds in saidsheets, said folding machine further including:

resilient mounting means for pivotably mounting a first roller on saidframe so that said first roller is adapted to pivot about a point onsaid frame; said resilient mounting means including a resilienttorsional bearing located at said pivot point on said frame, saidresilient torsional bearing causing a predetermined biasing torque onsaid means for pivotally mounting said first roller to thereby urge saidfirst roller toward a second roller so that a bite formed by said firstand second rollers produces appropriate folds in sheets of a giventhickness range.

1. A folding machine comprising a system of rotatable rollers mounted ona frame so that said rollers form bites therebetween for gripping andtransporting sheets to be folded, said folding machine including guidingmeans for guiding said sheets between said bites so that some of saidbites, upon gripping and transporting said sheets, cause folds in saidsheets, said folding machine further including a roller mounting meanscomprising: a roller mounting arm; a torsional bearing including aresilient means for mounting said roller mounting arm on said frame at afirst area along said roller mounting arm; and a roller mounting meansfor mounting a first roller on said roller-mounting arm at a second areaspaced from said first area along said roller mounting arm; wherein,said torsional bearing is preset so that said resilient means causes apredetermined biasing torque on said roller mounting arm to thereby urgesaid first roller toward a second roller so that a bite formed by saidfirst and second rollers produces appropriate folds in sheets of a giventhickness range.
 2. A folding machine as claimed in claim 1 wherein saidtorsional bearing comprises: an inner shaft; an outer housing; and acushioning member positioned between said inner shaft and said outerhousing; and wherein is further included a torque adjusting means foradjusting the angular position of said inner shaft to cause said properbiasing force.
 3. A folding machine as claimed in claim 2 wherein saidtorque adjusting means includes a gauge means for indicating the angularposition of said inner shaft.
 4. A folding machine as claimed in claim 3wherein said torque adjusting means includes an eleongated arm attachedto said inner shaft.
 5. A folding machine as claimed in claim 1 whereinis further included a roller positioning means for adjusting theposition of said roller.
 6. A folding machine as claimed in claim 5wherein said roller positioning means is for causing causes said rollerto rotate in an arc about a central axis of said torsional bearing.
 7. Afolding machine as claimed in claim 6 wherein said roller positioningmeans comprises a lever which pivots about said central axis of saidtorsional bearing, said lever being linked to said roller mounting armin such a manner as to cause said roller mounting arm to rotate aboutsaid central axis in an arc in the same manner that said lever rotatesabout said central axis.
 8. A folding machine as claimed in claim 7wherein said lever includes a table at one end thereof and a cradle atthe opposite end thereof, and wherein is further included a fixedbracket adjacent to said table whereby a piece of material insertedbetween said table and said bracket causes said roller to have apredetermined position.
 9. A folding machine as claimed in claim 8wherein said torsional bearing comprises: an inner shaft; an outerhousing; and a cushioning mEmber positioned between said inner shaft andouter housing; and wherein is further included a torque adjusting meansfor adjusting the angular position of said inner shaft to cause saidproper biasing force.
 10. A folding machine as claimed in claim 9wherein said adjusting means includes a gauge means for indicating theangular position of said inner shaft.
 11. A folding machine as claimedin claim 10 wherein said torque adjusting means includes an elongatedarm attached to said inner shaft.
 12. A folding machine as claimed inclaim 1 wherein said folding machine includes a series of rollers; and aplurality of elongated roller mounting arms and torsional bearings forrespectively mounting said rollers on said frame.
 13. A folding machineas claimed in claim 1 wherein said torsional bearing comprises: an innershaft; an outer housing; and a cushioning member positioned between saidinner shaft and said outer housing, said cushioning member producing ameasurement of approximately 50 on a durometer.
 14. A folding machine asin claim 1 wherein the pivot point of said torsional bearing is locatedat a fixed distance from the axis of rotation of said roller.
 15. Thefolding machine of claim 1 wherein said roller mounting means includesan axle for said first roller and said torsional biasing means comprisesan inner shaft, an outer housing, and a cushioning member positionedbetween said inner shaft and said outer housing; and wherein saidfolding machine further includes: means connecting said inner shaft ofsaid torsional bearing to said axle for maintaining a fixed distancebetween the center of said torsional bearing and said roller axle.
 16. Afolding machine comprising a system or rotatable rollers mounted on aframe so that said rollers form bites therebetween for gripping andtransporting sheets to be folded, said folding machine including guidingmeans for guiding said sheets between said bites so that some of saidbites, upon gripping and transporting said sheets, cause folds in saidsheets, said folding machine further including: resilient mounting meansfor pivotably mounting a first roller on said frame so that said firstroller is adapted to pivot about a point on said frame; said resilientmounting means including a resilient torsional bearing located at saidpivot point on said frame, said resilient torsional bearing causing apredetermined biasing torque on said means for pivotally mounting saidfirst roller to thereby urge said first roller toward a second roller sothat a bite formed by said first and second rollers produces appropriatefolds in sheets of a given thickness range.